U.S. patent number 4,587,535 [Application Number 06/641,591] was granted by the patent office on 1986-05-06 for liquid jet apparatus with pressure sensor for indicating absence/presence of liquid.
This patent grant is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Yoshitaka Watanabe.
United States Patent |
4,587,535 |
Watanabe |
May 6, 1986 |
**Please see images for:
( Certificate of Correction ) ** |
Liquid jet apparatus with pressure sensor for indicating
absence/presence of liquid
Abstract
An ink jet recording apparatus comprises: at least one ink jet
head to emit a recording ink; main and sub ink tanks to store the
ink which should be supplied to the head; a negative pressure
generating device to generate a negative pressure to supply the ink
from the sub ink tank into the head under the suction action; a
pressure sensor, provided in the ink passage, for detecting whether
the recording ink substantially remains or not in the sub ink tank
when the negative pressure generating device operates. In response
to a pressure variation in the ink passage, the pressure sensor
determines that no ink substantially remains in the sub ink tank
when the pressure in the ink passage is higher than a preset value,
thereby generating a detection signal to supplement a new ink into
the tank to a control circuit. Therefore, the absence of ink in the
tank can be certainly detected and the ink can be emitted in good
conditions, so that the recording can be smoothly performed by a
simple, cheap and small-sized apparatus.
Inventors: |
Watanabe; Yoshitaka (Tokyo,
JP) |
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
15608618 |
Appl.
No.: |
06/641,591 |
Filed: |
August 17, 1984 |
Foreign Application Priority Data
|
|
|
|
|
Aug 25, 1983 [JP] |
|
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58-155555 |
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Current U.S.
Class: |
347/23; 347/30;
73/303 |
Current CPC
Class: |
B41J
2/17566 (20130101); B41J 2002/17583 (20130101) |
Current International
Class: |
B41J
2/175 (20060101); G01D 015/16 (); G01F
023/00 () |
Field of
Search: |
;346/14PD,14IJ ;222/64
;73/303 ;137/209 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goldberg; E. A.
Assistant Examiner: Reinhart; Mark
Attorney, Agent or Firm: Fitzpatrick, Cella, Harper &
Scinto
Claims
What I claim is:
1. A liquid jet apparatus comprising:
liquid jet head means for emitting a liquid;
liquid storing means for storing a liquid to be supplied to said
head means;
pressure generating means for generating a negative pressure to
suck said liquid from said head means; and
detecting means for detecting the substantial presence and absence
of liquid in said storing means, said detecting means being
arranged to determine whether or not liquid is substantially
present in said storing means when a predetermined period of time
has elapsed after said pressure generating means operated.
2. An apparatus according to claim 1, wherein said detecting means
is arranged to detect the substantial presence and absence of
liquid in said storing means on the basis of a variation in
pressure in a liquid passage between said storing means and said
pressure generating means.
3. An apparatus according to claim 2, wherein said detecting means
is arranged to respond to a pressure variation in a liquid passage
between said head means and said pressure generating means.
4. An apparatus according to claim 2, wherein said detecting means
is arranged to respond to a pressure variation in a liquid passage
between said head means and said storing means.
5. An apparatus according to claim 2, wherein said detecting means
is arranged to determine that there is substantially no liquid
stored in said storing means when the pressure in said liquid
passage upon operation of said pressure generating means is lower
than a predetermined value.
6. An apparatus according to claim 5, further comprising capping
means for capping a liquid jet portion of said head means, wherein
said detecting means is provided in a part of said capping
means.
7. An apparatus according to claim 6, wherein said pressure
generating means is coupled to said capping means.
8. An apparatus according to claim 2, further comprising capping
means for capping a liquid jet portion of said head means, wherein
said detecting means is provided in a part of said capping
means.
9. An apparatus according to claim 8, wherein said pressure
generating means is coupled to said capping means.
10. An apparatus according to claim 1, further comprising capping
means for capping a liquid jet portion of said head means, wherein
said detecting means is provided in a part of said capping
means.
11. An apparatus according to claim 10, wherein said pressure
generating means is coupled to said capping means.
12. An apparatus according to claim 1, further comprising warning
means for generating a warning when it is detected that there is
substantially no liquid stored in said storing means.
13. An ink jet recording apparatus comprising:
at least one ink jet head having an ink emitting orifice;
an ink tank communicated with said head;
capping means for capping the orifice of said head;
suction means, coupled to said capping means, for sucking ink in
said tank through said capping means; and
detecting means, provided for said capping means, for detecting the
substantial presence and absence of ink in said ink tank, said
detecting means being arranged to determine whether or not ink is
substantially present in said ink tank when a predetermined period
of time has elapsed after said suction means operated.
14. An apparatus according to claim 13, wherein said detecting
means includes a pressure sensor.
15. An apparatus according to claim 14, wherein said detecting
means further includes a discriminating circuit for determining
that there is substantially no ink in said ink tank when the
pressure detected through said pressure sensor is lower than a
predetermined value.
16. An apparatus according to claim 15, further comprising warning
means for generating a warning when it is determined that there is
substantially no ink in said ink tank in response to said
discriminating circuit.
17. An ink jet recording apparatus using an exchangeable ink
cartridge, comprising:
at least one ink jet head having an ink emitting orifice;
an ink tank communicated with said head;
communicating means for communicating said ink tank with said ink
cartridge;
capping means for capping the orifice of said head;
suction means, coupled to said capping means, for sucking ink
through said capping means; and
detecting means, provided for said capping means, for detecting the
substantial presence and absence of ink in said ink cartridge, said
detecting means being arranged to determine whether or not ink is
substantially present in said ink cartridge when a predetermined
period of time has elapsed after said suction means operated.
18. An apparatus according to claim 17, wherein said detecting
means includes a pressure sensor.
19. An apparatus according to claim 18, wherein said detecting
means further includes a discriminating circuit for determining
that there is substantially no ink in said ink cartridge when the
pressure detected through said pressure sensor is lower than a
predetermined value.
20. An apparatus according to claim 19, further comprising warning
means for generating a warning when it is determined that there is
substantially no ink in said ink cartridge in response to said
discriminating circuit.
21. An apparatus according to claim 17, wherein said suction means
has a first operating mode for generating a first negative pressure
to recover said ink jet head from an unstable ink emitting state
and a second operating mode for generating a second negative
pressure to supply ink to said ink tank from an exchanged ink
cartridge, said second negative pressure being different from said
first negative pressure.
22. An apparatus according to claim 21, wherein said detecting
means is arranged to operate in the first operating mode of said
suction means.
23. An apparatus according to claim 21, wherein said first negative
pressure is lower than said second negative pressure.
24. An ink jet recording apparatus using an exchangeable ink
cartridge, comprising:
at least one ink jet head having an ink emitting orifice;
an ink tank communicated with said head;
communicating means for communicating said ink tank with said ink
cartridge;
capping means for capping the orifice of said head; and
suction means, coupled to said capping means, for sucking ink
through said capping means, said suction means having a first
operating mode for generating a first negative pressure to recover
said ink jet head from an unstable ink emitting state and a second
operating mode for generating a second negative pressure to supply
ink to said ink tank from an exchanged ink cartridge, said second
negative pressure being different from said first negative
pressure.
25. An apparatus according to claim 24, wherein said first negative
pressure is lower than said second negative pressure.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid jet apparatus such as,
e.g., an ink jet recording apparatus and, more particularly, to
means for detecting the substantial presence and absence of the
liquid stored in the liquid storing means.
2. Description of the Prior Art
Liquid jet recording apparatuses such as an ink jet recording
apparatus and the like are getting most of the attention as new
recording means since they have advantages such that direct
recording is possible, coloration is easy and noise is reduced.
Particularly, on-demand type ink jet recording apparatus is
becoming a principal full color printer technology since it is
cheap and can be miniaturized.
However, conventionally, this kind of recording apparatus has the
drawback that the emission of ink becomes unstable due to an
increase in viscosity of ink since the volatile substance in the
ink at the point of the recording head (ink jet head) may
evaporate. Further, since it is necessary to form the ink tank, or
recording liquid storing means, of flexible material, it is
difficult to detect whether or not ink remains in the tank.
Therefore, there is another drawback namely misrecording due to
lack of ink. In the former case, it has been tried to remove the
ink having increased viscosity from the orifice opening at the
point of the head by an apparatus for preventing choking, so that a
certain extent of effect is obtained. However, when the choking
preventing apparatus and apparatus for detecting the amount of
remaining ink in the tank are individually provided, the equipment
becomes complicated, causing the size and cost of the apparatus to
increase. In particular, an increase in the number of kinds of inks
used for coloration or the like exacerbates this tendency. On the
other hand, when the point of the head is capped for prevention of
drying of the head, the ink meniscus at the point of the head
retracts, thereby causing a drawback such that the recording
(printing) becomes unstable.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
liquid jet apparatus equipped with means for certainly detecting
whether the liquid substantially remains or not in the liquid
storing means by a simple constitution.
The meaning of substantially no liquid remains in the liquid
storing means or the like includes the case where liquid of a very
small quantity, such that liquid cannot be sufficiently emitted, in
addition to the state whereby no liquid exists at all in the
storing means.
According to an embodiment embodying the aspect of the invention
under such object, the liquid jet apparatus comprises: jet head
means for emitting a liquid; storing means for storing the liquid
which should be supplied to the head means; pressure generating
means for generating a pressure to feed the liquid to the head
means from the storing means; and detecting means for detecting the
substantial presence and absence of the liquid stored in the
storing means when the pressure generating means is operating.
In the embodiment, the pressure generating means is constituted so
as to generate a negative pressure such as, for example, a suction
mechanism, while the detecting means is constituted so as to detect
the substantial presence and absence of the stored liquid by
detecting a variation in pressure in the liquid passage between the
pressure generating means and the storing means.
Another object of the present invention is to provide a novel
liquid jet apparatus which can simultaneously perform both
detection of the substantial presence and absence of the liquid
stored in the storing means and prevention of the choking of the
head.
According to an embodiment under such an object, the detecting
means is provided in a capping device for the head means in the
form of pressure detecting means, and at this time the pressure
generating means is coupled as suction means for generating a
negative pressure to the capping device.
The above and other objects, features and advantages of the present
invention will be apparent from the following detailed description
in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention will be described
hereinbelow with reference to the accompanying drawings, in
which:
FIG. 1 is a constitutional diagram of an embodiment in the case
where the present invention is applied to a liquid jet recording
apparatus;
FIG. 2 illustrates cross sectional views showing the details of a
capping device and a head unit in FIG. 1;
FIG. 3 is a block diagram of the control system of the apparatus of
FIG. 1;
FIG. 4 is a graph showing the pressure change characteristics of a
pressure chamber in the capping device in FIGS. 1 and 2;
FIGS. 5A and 5B are a set of flow charts for explaining the
operation of the apparatus shown in FIGS. 1 to 3; and
FIG. 5 is a diagram showing the arrangement of FIGS. 5A and 5B.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With respect to an example whereby means for sensing a variation in
pressure is provided in the meniscus recovery system, the
description will be made hereinbelow in the sequence of the
constitution and operation of one example of a liquid jet recording
apparatus to which the invention is employed.
In FIG. 1, a pulse motor M controls the operations of a capping
device and a pump which will be explained later. A reference
numeral 1 denotes a liquid jet head unit including at least one
liquid jet head; 2 denotes a recording liquid storing member of the
exchangeable cartridge type (hereinbelow, referred to as a main ink
tank); 3 denotes a flexible tube for supplying a recording liquid
(hereinafter, may be simply referred to as an ink) from the main
ink tank 2 to the head unit 1; and 4 denotes a capping device
equipped with pressure detecting means and its details will be
explained later in conjunction with FIG. 2. A tube 5 couples the
head unit 1 through the capping device 4 with a suction pump PU
which will be mentioned later. A spring 6 is supported to the fixed
portion of the apparatus and presses the capping device 4 equipped
with the pressure detecting means in the direction of the head unit
1. A gear 7 is driven by the pulse motor M. A lever 7a is fixed to
the gear 7 and is rotated integrally with the gear 7. The lever 7a
comes into engagement with a lever 4e provided for the capping
device 4, thereby restricting the location of the capping device 4.
A slide lever 8 has a rack portion 8a adapted to engage the gear 7
and long holes 8b and 8c and is slid to the right and left in the
diagram along pins 9a and 9b planted in the fixed portion of the
apparatus in association with the rotations of the pulse motor M
and gear 7. Two-level different shapes 8f and 8 g are formed at the
lower portion of the slide lever 8 due to chambered portions 8d and
8e.
A numeral 10 represents a cylinder of the suction pump PU; 11
denotes a piston; 11a and 11b respectively denote a through hole
and a valve thereof; 12 a spring for pressing the piston 11
upwardly in the diagram; 13 a tube for coupling the pump PU with a
sub ink tank 1e of the head unit 1 (FIG. 2); and 15 denotes a drain
tube coupled to a drain tank (not shown).
A numeral 14 denotes a head moving device for moving the head unit
1 in the direction perpendicular to the drawing plane for
recording. In this case, the capping device 4 is arranged so as to
face the head unit 1 when the head unit 1 is moved to a
predetermined location (home position) which is deviated by a
predetermined range for recording.
FIG. 2 shows cross sectional views of the head unit 1 and capping
device 4 in FIG. 1, in which a numeral 1a denotes at least one
liquid jet head which has an orifice opening 1c and consists of a
nozzle 1b and a cylindrical piezo element 1d; le denotes the sub
ink tank; and RI indicates an ink in the subtank 1e. The sub tank
1e is coupled to main ink tank 2 and pump PU through the tubes 3
and 13, respectively.
A numeral 4d denotes a cap portion of the capping device; 4a a
pressure chamber communicated with the cap portion; 4b a pressure
sensor which is constituted by e.g., a strain gauge or a
piezoelectric element or the like and is attached to an opening 4a'
of the pressure chamber 4a by means of an adhesive or the like to
prevent the leakage of the ink; and 4c an output terminal of the
sensor 4b.
FIG. 3 shows the control system of the liquid jet recording
apparatus of FIG. 1, in which 101 denotes a control circuit; 102 a
driver for the motor M; 103 a timer; 104 a pressure sensor; 105 a
comparator; and 106 a display.
Next, the operation of the apparatus of FIGS. 1 to 3 will be
explained with reference to the graph of the pressure change
characteristic in the pressure chamber 4a shown in FIG. 4 and
flowcharts shown in FIGS. 5A and 5B.
(1) When a recording start signal ST is inputted to the control
circuit 101, the pulse motor M is rotated in a forward direction by
the control circuit 101 through the motor driver 102 by only an
amount corresponding to a predetermined number N.sub.1 of pulses
(steps 201 and 202 in FIG. 5A). The gear 7 is rotated
counterclockwise in FIG. 1 in association with the forward rotation
of the pulse motor M, so that the capping device 4 to which the
pressure detecting means (4a, 4b) are attached goes away from the
head unit 1 by the levers 7a and 4e. Thereafter, the head unit 1 is
moved by the head moving device 14, thereby allowing the ink to be
emitted in association with this movement, so that the recording is
performed as in the usual manner (step 203).
(2) After the completion of the recording, the head unit 1 is
returned to the home position. Thereafter, when a recording end
signal END is inputted to the control circuit 101, the motor M is
rotated in a backward direction by only an amount corresponding to
the pulse number N.sub.1 (steps 204 and 205). This allows the gear
7 to be rotated clockwise, so that the capping device 4 is moved to
the right in FIG. 1 due to the operation opposite to (1) and the
cap portion 4d is coupled to the point of the head unit 1. When the
gear 7 is further rotated, the slide lever 8 is moved to the left
due to the engagement between the rack portion 8a and the gear 7,
thereby depressing the piston 11 of the pump PU to a level
indicated at B. At this time, the pressure in the pressure chamber
4a becomes a level indicated at A in FIG. 4. The driving of the
pulse motor M is stopped in this state and the slide lever 8 is
held at this location. The location of the lever 8 may be kept due
to the torque of the pulse motor M without cutting off the
excitation of the motor M for this purpose. Or, it may be
maintained due to the frictional force between the slide lever 8
and the piston 11 pressed upwardly by the spring 12.
(3) After a time T.sub.0 (FIG. 4) which is determined by setting
the timer 103 has elasped, the pressure in the pressure chamber 4a
changes as the time passes as indicated by the solid line in FIG. 4
by supplying the ink into the sub ink tank 1e if the ink RI remains
in the main ink tank 2 as the main recording liquid storing
chamber; as a result, it returns to the atmospheric pressure. On
the contrary, when no ink RI remains in the main ink tank 2, the
above-mentioned pressure changes as indicated by the broken line
and stops at a pressure of P.sub.0 and will not return to the
atmospheric pressure.
Therefore, an output of the pressure sensor 104 (e.g., strain gauge
4b in FIG. 2) is inputted to the comparator 105 and is compared
with the preset value P.sub.0, thereby enabling the presence and
absence of the ink in the main ink tank 2 to be detected (step
206). The presence and absence of the ink denote that the recording
liquid (ink) substantially remains or not as mentioned before.
(4) When a comparison output of the comparator 105 is inputted to
the control circuit 101, in the case where it is a signal
indicative of the absence of ink, the control circuit 101 allows
the display 106 to indicate "no ink" (visual or audible warning
indication may be possible). The control circuit 101 also allows
the pulse motor M to be rotated in the forward direction and
permits the capping device 4 to be detached from the head unit 1
and stops the operation of the whole system (steps 207 to 209; the
first state). On the other hand, when a signal representative of
the presence of the ink is inputted, in more detail, when the input
signal indicates that an output signal of the sensor 104 is larger
than the preset value P.sub.0, the capped state is held until the
next recording start signal ST is inputted (steps 207 and 201; the
second state).
Practically speaking, as mentioned above, when the recording start
signal ST is inputted, the motor M is rotated in the forward
direction to detach the capping device 4 from the head unit 1. At
the same time, a small quantity of ink remaining the upper chamber
of the pump PU is moved to the lower chamber through the through
hole 11a and valve 11b due to the upward movement of the piston 11.
This ink is drained to a drain tank (not shown) through the drain
tube 15 at the time of next capping, i.e., when the pressure is
detected.
According to the foregoing embodiment, since the orifice opening 1c
of the nozzle 1b of the head 1a is held with the cap attached (in
the closed state), it is possible to prevent the volatile substance
in the ink from being evaporated from the point of the orifice.
Further, even when the meniscus of the ink is moved backward when
the nozzle is capped, the meniscus is returned because of the
suction due to the negative pressure of the pump PU. Therefore, it
is possible to prevent unstable ink emission due to an increase in
viscosity of the ink and the backward movement of the meniscus at
the time of next recording.
(5) When the user exchanges to a new main ink tank in the first
state of the above process (4), in response to the input of an ink
exchange signal MT at that time (a signal by a manual switch or the
like, not shown), the control circuit 101 permits the pulse motor M
to be rotated in the backward direction through the motor driver
102 by only an amount corresponding to a predetermined number
N.sub.2 of pulses larger than the above-mentioned number N.sub.1
(steps 210 and 211). Due to this, the capping operation for the
head unit 1 and the operation for depressing the piston of the pump
PU are carried out similarly to the process (2). However, since a
rotational amount of the pulse motor M is large in this case, the
slide lever 8 is moved until the second state level-different
portion 8g depresses the piston 11, so that the piston 11 descends
to the level C. Consequently, the pump PU generates a negative
pressure larger than that by the ordinary operation, thereby
supplying a large quantity of ink RI from the main ink tank 2 to
the sub ink tank 1e. Thus, the head 1a is recovered such that the
ink emission can be preferably performed.
(6) After the elapse of a predetermined time interval, the output
of the pressure sensor 104 is compared with the preset value
P.sub.0 by the comparator 105, thereby detecting the presence and
absence of the remaining ink RI in the main ink tank 2 (steps 212
and 213). In this case also, the presence and absence of the ink
denote that the recording liquid (ink) substantially exists or not
similarly to the above. As a result, when no ink RI remains, the
operations corresponding to the steps 208 to 211 are repeated.
However, when the ink RI remains, the indication by the display 106
is turned off and the capped state is held until the next recording
start signal ST is inputted (step 214). When the next recording
start signal ST is inputted, the pulse motor M is rotated in the
forward direction by only an amount corresponding to the pulse
number N.sub.2, so that the capping device 4 is removed from the
head unit 1 and the recording is executed similarly to the above
(steps 201A to 203A).
In the above embodiment, the pressure variation sensing means has
been provided in the ink meniscus recovery system and, as the
embodiment of this invention, this constitution is considered to be
most advantageous from the viewpoints of simplicity of constitution
and certainty of detection. However, the invention can be also
implemented by providing the pressure variation sensing means at
any portion in the recording liquid supplying system (e.g., in the
tube 3 or 13 in FIG. 1).
As described above in detail, according to the invention, in the
liquid jet apparatus, a variation in pressure at any portion in the
liquid supplying system or meniscus recovery system is sensed when
the pressure generating means operates, and the liquid stored in
the liquid storing means is detected to see if it substantially
remains or not. Therefore, it is possible to certainly detect
whether the liquid in the liquid storing means substantially
remains or not without individually providing means for detecting a
quantity of remaining liquid. Also, the liquid can be emitted in
the good condition. The apparatus is simple and it can be
miniaturized and the cost can be reduced.
* * * * *